Bottom Line:
In vitro investigations demonstrated the ability of multifunctional nanoparticles to preserve the photophysical properties of the encapsulated photosensitizer and to confer photosensitivity to MDA-MB-231 cancer cells related to photosensitizer concentration and light dose.Using binding test, we revealed the ability of peptide-functionalized nanoparticles to target NRP-1 recombinant protein.Real-time MRI analysis revealed the ability of the targeting peptide to confer specific intratumoral retention of the multifunctional nanoparticles.

ABSTRACTPhotodynamic therapy (PDT) is an emerging theranostic modality for various cancer as well as non-cancer diseases. Its efficiency is mainly based on a selective accumulation of PDT and imaging agents in tumor tissue. The vascular effect is widely accepted to play a major role in tumor eradication by PDT. To promote this vascular effect, we previously demonstrated the interest of using an active- targeting strategy targeting neuropilin-1 (NRP-1), mainly over-expressed by tumor angiogenic vessels. For an integrated vascular-targeted PDT with magnetic resonance imaging (MRI) of cancer, we developed multifunctional gadolinium-based nanoparticles consisting of a surface-localized tumor vasculature targeting NRP-1 peptide and polysiloxane nanoparticles with gadolinium chelated by DOTA derivatives on the surface and a chlorin as photosensitizer. The nanoparticles were surface-functionalized with hydrophilic DOTA chelates and also used as a scaffold for the targeting peptide grafting. In vitro investigations demonstrated the ability of multifunctional nanoparticles to preserve the photophysical properties of the encapsulated photosensitizer and to confer photosensitivity to MDA-MB-231 cancer cells related to photosensitizer concentration and light dose. Using binding test, we revealed the ability of peptide-functionalized nanoparticles to target NRP-1 recombinant protein. Importantly, after intravenous injection of the multifunctional nanoparticles in rats bearing intracranial U87 glioblastoma, a positive MRI contrast enhancement was specifically observed in tumor tissue. Real-time MRI analysis revealed the ability of the targeting peptide to confer specific intratumoral retention of the multifunctional nanoparticles.

Figure 5: Kinetics of photo-induced cytotoxicity of nanoparticles according to real-time impedance-based analysis. MDA-MB-231 cells were monitored for 24 h during interaction with NP-TPC-ATWLPPR (A, B, C) or NP (D) at the indicated concentrations of photosensitizer or the corresponding concentration of gadolinium oxide for the control NP (left panel). Following washing, cells were exposed to various light doses (A: 1 J/cm2, B: 5 J/cm2, C and D: 10 J/cm2) (right panel). Presented cell index values are the mean of 6 replicates.

Mentions:
The dynamic response of the MDA-MB-231 cancer cells exposed to increasing concentrations of NP-TPC-ATWLPPR and various doses of light was also monitored using real-time impedance-based analysis (Fig. 5A-B-C). As expected according to our findings from dark cytotoxicity kinetics (Fig. 3B), no decrease in cell index values was observed during the first 24 h post-exposure to nanoparticles before light irradiation (Fig. 5, left panel). However, cell index kinetics obtained during the time interval from 25 to 55 h post-irradiation clearly showed discriminant profiles (Fig. 5A-B-C, right panel). According to nanoparticles concentrations and light doses, kinetic profiles showed a transient or a persistent decrease of normalized cell index (Fig. 5A-B-C, right panel). Beside the nanoparticles concentration- and the light dose-dependent photocytotoxicity, distinct phases of cell response along the post-irradiation period can be highlighted, thus showing time-dependent cellular effect. Interestingly, as shown on Fig. 5-D (right panel), photosensitizer-free nanoparticles (NP) showed no decrease of cell index values whatever the concentrations even after light irradiation with 10 J/cm2 as compared to untreated cells. This means that the nanoparticles-induced photocytotoxicity relies on the photoactivation of the photosensitizer molecules grafted inside the nanoparticles.

Figure 5: Kinetics of photo-induced cytotoxicity of nanoparticles according to real-time impedance-based analysis. MDA-MB-231 cells were monitored for 24 h during interaction with NP-TPC-ATWLPPR (A, B, C) or NP (D) at the indicated concentrations of photosensitizer or the corresponding concentration of gadolinium oxide for the control NP (left panel). Following washing, cells were exposed to various light doses (A: 1 J/cm2, B: 5 J/cm2, C and D: 10 J/cm2) (right panel). Presented cell index values are the mean of 6 replicates.

Mentions:
The dynamic response of the MDA-MB-231 cancer cells exposed to increasing concentrations of NP-TPC-ATWLPPR and various doses of light was also monitored using real-time impedance-based analysis (Fig. 5A-B-C). As expected according to our findings from dark cytotoxicity kinetics (Fig. 3B), no decrease in cell index values was observed during the first 24 h post-exposure to nanoparticles before light irradiation (Fig. 5, left panel). However, cell index kinetics obtained during the time interval from 25 to 55 h post-irradiation clearly showed discriminant profiles (Fig. 5A-B-C, right panel). According to nanoparticles concentrations and light doses, kinetic profiles showed a transient or a persistent decrease of normalized cell index (Fig. 5A-B-C, right panel). Beside the nanoparticles concentration- and the light dose-dependent photocytotoxicity, distinct phases of cell response along the post-irradiation period can be highlighted, thus showing time-dependent cellular effect. Interestingly, as shown on Fig. 5-D (right panel), photosensitizer-free nanoparticles (NP) showed no decrease of cell index values whatever the concentrations even after light irradiation with 10 J/cm2 as compared to untreated cells. This means that the nanoparticles-induced photocytotoxicity relies on the photoactivation of the photosensitizer molecules grafted inside the nanoparticles.

Bottom Line:
In vitro investigations demonstrated the ability of multifunctional nanoparticles to preserve the photophysical properties of the encapsulated photosensitizer and to confer photosensitivity to MDA-MB-231 cancer cells related to photosensitizer concentration and light dose.Using binding test, we revealed the ability of peptide-functionalized nanoparticles to target NRP-1 recombinant protein.Real-time MRI analysis revealed the ability of the targeting peptide to confer specific intratumoral retention of the multifunctional nanoparticles.

ABSTRACTPhotodynamic therapy (PDT) is an emerging theranostic modality for various cancer as well as non-cancer diseases. Its efficiency is mainly based on a selective accumulation of PDT and imaging agents in tumor tissue. The vascular effect is widely accepted to play a major role in tumor eradication by PDT. To promote this vascular effect, we previously demonstrated the interest of using an active- targeting strategy targeting neuropilin-1 (NRP-1), mainly over-expressed by tumor angiogenic vessels. For an integrated vascular-targeted PDT with magnetic resonance imaging (MRI) of cancer, we developed multifunctional gadolinium-based nanoparticles consisting of a surface-localized tumor vasculature targeting NRP-1 peptide and polysiloxane nanoparticles with gadolinium chelated by DOTA derivatives on the surface and a chlorin as photosensitizer. The nanoparticles were surface-functionalized with hydrophilic DOTA chelates and also used as a scaffold for the targeting peptide grafting. In vitro investigations demonstrated the ability of multifunctional nanoparticles to preserve the photophysical properties of the encapsulated photosensitizer and to confer photosensitivity to MDA-MB-231 cancer cells related to photosensitizer concentration and light dose. Using binding test, we revealed the ability of peptide-functionalized nanoparticles to target NRP-1 recombinant protein. Importantly, after intravenous injection of the multifunctional nanoparticles in rats bearing intracranial U87 glioblastoma, a positive MRI contrast enhancement was specifically observed in tumor tissue. Real-time MRI analysis revealed the ability of the targeting peptide to confer specific intratumoral retention of the multifunctional nanoparticles.